The invention relates to a device for push-pull transmission of an item of binary information across line groups having at least three or more lines. Push-pull transmitters and push-pull receivers are connected to these lines.
The push-pull principle is used with preference for transmitting data between two opposite stations in which equal ground potentials are not assured. A system for transmitting push-pull signals on a 2 wire line in full duplex operation is disclosed in U.S. Pat. No. 4,112,253, incorporated herein by reference. The transmission of push-pull signals on a double or 2 wire line at least largely suppresses push-push interferences since at the receiving end an analysis is only carried out on the potential difference between the two lines on the basis of the sign of which the information is formed.
The parallel transmission of a plurality of bits, for example between various units within a data processing system across a corresponding number of double or 2 wire lines, involves a considerable expense in terms of lines and line plugs, the unpleasant manifestation of which is a large space requirement and high costs.
It is generally known to form a so-called phantom circuit from two double lines and thus to improve the ratio of the information which can be simultaneously transmitted to the overall number of physical lines--in the following referred to as transmission capacity--from 0.5 bits to 0.75 bits.